Preparation And Application Of High Performance Fiber Reinforced Nylon 66 Composites

High performance fiber reinforced nylon 66 composite material has the advantages of low density,high strength and good dimensional stability.It is widely used in aerospace,wind turbine blades,automobile industry and other fields.However,the composite has a series of problems,such as harsh processing technology,poor interface bonding,high cost and performance improvement.The glass fiber reinforced nylon 66 composite material,carbon fiber reinforced nylon 66 composite material and glassy carbon hybrid fiber reinforced nylon 66 composite material with excellent properties were prepared by means of twin screw extruder melting blending,adding self-made volume enhancing agent and setting up appropriate processing technology.The density and micromorphology of the composite were characterized,and the melting and crystallization behavior,mechanical properties,thermogravimetric properties,melting index and other application properties were tested and analyzed.The relationship between structure and performance was discussed,and the application was discussed.(1)The density of high performance reinforced nylon 66 composites ranges from1.3-1.45g/cm~3,far less than the density of metal,achieving the purpose of lightweight.Scanning electron microscopy of the sample section showed that the fibers in the composite material system were fully bonded to the nylon 66 matrix,and the fracture surface was rough with the fibers pulled out.The polarizing microscope images of composite materials were analyzed by the software Nano Measurer,which showed that the length of the fibers in the composite materials was between 0.5 and 0.7mm,and the trend of decreasing gradually with the increase of fiber content.(2)The mechanical property test found that the PA66/GF composite had the best mechanical properties when the glass fiber content reached 30%.The tensile strength of the composite material was 147.4MPa,which was 75%higher than that of PA66.The bending strength reached 202MPa,which was about 112%higher than PA66;the bending modulus was increased to 7783.3MPa,which was about 175%higher.The PA66/CF composite had the best mechanical properties when 4 bundles of carbon fiber were added.The tensile strength of the composite was 200.2MPa,which was113.2MPa higher than that of PA66.The bending strength was 280.2MPa,which was190.3MPa higher than that of PA66;the bending modulus was 13560.8MPa,which was 10628.7Mpa higher than PA66;the impact strength was 14.8 KJ/m~2,which was6.3 KJ/m~2 higher than PA66.When two bundles of carbon fiber and one bundle of glass fiber were added,the comprehensive mechanical properties of PA66/CG composites were the best.The tensile strength of PA66 composites was 180.0MPa,which was 106.9%higher than the original sample of nylon 66,and the elongation at break was 2.9%.(3)Differential scanning calorimeter(DSC)and TGA were used to study its thermal performance.DSC results showed that with the addition of fibers,the melting point of composites changed little,but the crystallization temperature increased,indicating that the addition of fibers played a heterogeneous nucleation role and changed the nucleation mechanism.Thermogravimetric analysis showed that the maximum thermal degradation rate of the composite was slightly higher than that of nylon 66.The fluidity of the composite was characterized by melt index.It was found that the melt index decreased with the increase of fiber content.The performance indexes of PA66/GF composite material with glass fiber content of 30%prepared in this paper have been up to the standard and have been recognized by the customer.The other two high performance fiber reinforced nylon66 composites have good application prospects and are currently in the application exploration stage.